I realize that this post is fairly old, but it's one of the first things that came up when I searched for "electronics montreal". If anyone is interested, I made a map of the electronics shops that I know of in Montreal. Here's the URL:

I haven't been down to Active Surplus in a while, heard they moved and are a lot smaller now. Too bad as they had lots of neat stuff.

KW surplus in Kitchener is still pretty good and along the lines of Active, KW also used to sell scrap plexiglass and lucite which was handy for projects. They also sold lots of army surplus clothing like chemical warfare suits...

Sadly long gone was Forest City surplus in London Ont, one year they had a bunch of surplus AV Roe binders from the Arrow project. They also had the mechanical gorilla like Active.

If you want semiconductors, the best source isn't local:DigiKey Corp. | Electronic Components Distributor | Canada Home Page
They'll ship you a single transistor or a thousand, overnight for $8 brokerage and duty included form the US. MAke sure you use the Canadian site as the prices on it include duty and brokerage. Parts ordered before 7PM central ALWAYS arrive the next morning. Once you try it, you'll be addicted.